Martenscypridopsis n. gen. and Martenscypridopsis materia n. sp. from Algerian inland waters are described. The new genus belongs to the group of genera in the subfamily Cypridopsinae where the right valve overlaps the left one both anteriorly and ventrally ; it is also the second genus within the subfamily where both sexes completely lack the furca. The new genus includes also the species Martenscypridopsis pygmea (Sars, 1924) n. comb., from South and Central Africa.